1. Field of the Invention
The present invention relates to an information recording apparatus which records information signals such as image information, sound information, and the like on a recording medium, and has a post recording function to add new information to the recording medium on which a recording has been made.
2. Description of the Prior Art
The following specification shall explain the present invention, referring to an example of a video tape recorder (hereinafter referred to as VTR) in which a magnetic tape and rotating magnetic heads are used.
FIG. 1 shows a general arrangement of a conventional VTR. That is, a cassette 1, a magnetic tape 2, rotating magnetic heads 3, 4, a capstan 9, and a pinch roller 8, wherein the tape 2 is held in a pressure contacting manner by the capstan 9 and the pinch roller 8 and is fed in the direction of an arrow 10 with a constant speed. The rotating magnetic heads 3, 4 rotate in the direction of an arrow 11 with a constant speed. Also shown are a total width erasing head 5 for the video tape, a sound erasing head 6, and a fixed head 7 which has a sound recording and reproduction head, and a head to record and reproduce CTL (control) signals.
FIG. 2 shows a tape pattern recorded by the apparatus shown in FIG. 1, including a CTL signal recording track 12, a sound recording track 13, and a track 14 at which image signals are recorded azimuthally. As shown therein, image signals are recorded at a slanted magnetic locus on a running magnetic tape by rotating magnetic heads. Also, sound signals are recorded by a fixed head on a sound track provided at an edge part in the travel direction of the magnetic tape.
In this system, when a post or re-recording is done, sound signals are erased by the sound erasing head 6 which can erase the sound track only, and new sound signals are recorded by the sound recording fixed head for making a post recording.
In order to reduce the amount of magnetic tape consumed and to reduce the size and weight of the tape cassette and the apparatus, the width of the recording locus is made narrower and the running speed of the magnetic tape is made slower by intensifying the recording density of image signals. However, when the running speed of the magnetic tape is extremely slow, it has been difficult to secure sufficient frequency characteristics for the sound signals by the fixed head. Therefore, there has been a method developed to record and reproduce synthesized signals of image signals and sound signals by the same rotating magnetic head or heads.
FIG. 3 shows a tape pattern recorded in such a method, including a CTL (control) signal recording track 15, and a track 16 on which synthesized signals of image and sound are azimuthally recorded.
FIG. 4 is a diagram illustrating an example of zones or bands of image sound signals, including a color signal 17 being converted to a low zone, a brightness signal 19 being FM modulated, and a sound signal 18 being FM modulated.
However, since image signals and sound signals are both synthesized and recorded, it is impossible to make a post recording of sound signals only.
An object of the present invention is to provide an information recording apparatus in which the abovementioned shortcoming is eliminated.
That is, said object is to provide an information recording apparatus which can record signals obtained by mixing or selecting reproduced information which is recorded at a prescribed position on a recording medium, and new information to be added to the recorded information on the medium, at the prescribed position at which the reproduced information was recorded on the medium.